1. Field of the Invention
The present invention relates to a silver halide emulsion and a photographic light-sensitive material using the same and, more particularly, to a tabular silver halide photographic emulsion having high photographic sensitivity and a photographic light-sensitive material using the same.
2. Description of the Related Art
Methods of manufacturing and using tabular silver halide grains (to be also referred to as simply "tabular grains" hereinafter) are disclosed in, e.g., U.S. Pat. Nos. 4,434,226, 4,439,520, 4,414,310, 4,433,048, 4,414,306, and 4,459,353. The tabular grain is known for its various advantages such as high sensitivity including improvement in color sensitizing efficiency obtained by a sensitizing dye, improvement in a sensitivity/graininess relationship, improvement in sharpness obtained by unique optical properties of the tabular grain, and improvement in covering power.
In recent years, however, as the sensitivity of a silver halide color light-sensitive material has been increased and its small formatting has progressed, a strong demand has arisen for a color photographic light-sensitive material having high sensitivity and high image quality.
For this reason, although a silver halide emulsion having higher sensitivity and better graininess is required, no conventional tabular silver halide emulsion can satisfy the above requirements, and a demand has arisen for an emulsion having higher performance.
Observation of dislocations in silver halide grains are described in, e.g.:
1. C. R. Berry, J. Appl. Phys., 27, 636 (1956) PA1 2. C. R. Berry, D. C. Skilman, J. Appl. Phys., 35, 2165 (1964) PA1 3. J. F. Hamilton, Phot. Sci. Eng., 11, 57 (1967) PA1 4. T. Shiozawa, J. Soc. Phot. Sci. Jap. 34, (1971) PA1 5. T. Shiozawa, J. Soc. Phot. Sci. Jap., 35, 213 (1972) PA1 (1) A silver halide photographic emulsion containing tabular silver halide grains which have an aspect ratio of 2 or more and in which dislocations are concentrated about the corners of the grain. PA1 (2) A silver halide photographic emulsion described in item (1), wherein tabular silver halide grains having a grain thickness of less than 0.5 .mu.m, a grain size of 0.3 .mu.m or more, and an aspect ratio of 2 or more account for at least 50% of a total projected area of all silver halide grains in the emulsion. PA1 (3) A method of manufacturing a silver halide photographic emulsion described in item (2), comprising the steps of junctioning silver iodide or a silver halide having a high silver iodide content to the corners of tabular silver halide grain directly or via halide conversion using iodide ions, thereby forming junctioned silver halide grains, and subsequently growing the junctioned tabular grains. PA1 (4) A photographic light-sensitive material having at least two light-sensitive silver halide emulsion layers having different color sensitivities on a support, wherein at least one of the emulsion layers contains a silver halide photographic emulsion described in item (2) and at least one coupler which couples with the oxidized form of a color developing agent to form a dye.
These references describe that dislocations in crystals can be observed by an X-ray diffraction method or a cryro-transmission electron microscopic method and various dislocations can be formed in crystals by giving distortion to the crystals.
In these references, dislocations are not formed in silver halide grains during formation of a photographic emulsion on purpose. JP-A-63-220238 ("JP-A" means unexamined published Japanese patent application) and JP-A-1-201649, however, describe silver halide grains in which dislocations are formed on purpose. According to these patent specifications, tabular grains having dislocation lines to some extent are superior to tabular grains having no dislocation lines in photographic properties such as sensitivity and reciprocity. In addition, good sharpness and graininess can be imparted to a light-sensitive material by using these tabular grains. However, these tabular grains are still unsatisfactory.